GMT Aluminum M4 O-ring nozzle (21.00mm)

This is an aluminum nozzle with O-ring for M4 series rifles. The O-ring stops air from leaking between the cylinder head and nozzle, all stock nozzle don't have this. This can increase FPS quite a lot depending on how much air is leaking. Since this doesn't put any more stress on the motor this won't affect your rate of fire like a stiffer spring or spring spacer.

Features:
- Aluminum construction
- O-ring increases FPS with no loss of ROF
- Total length 21.00 mm